/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.beam.sdk.extensions.gcp.util.channels;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.WritableByteChannel;
import java.util.function.Consumer;
import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.annotations.VisibleForTesting;
import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions;

public class CountingWritableByteChannel implements WritableByteChannel {
  private final WritableByteChannel delegate;
  private final Consumer<Integer> bytesWrittenConsumer;

  // since it's equivalent to directly using the delegate, there's no point in using this variant
  // elsewhere than in tests
  @VisibleForTesting
  public static CountingWritableByteChannel createWithNoOpConsumer(WritableByteChannel delegate) {
    return new CountingWritableByteChannel(delegate, __ -> {});
  }

  public CountingWritableByteChannel(
      WritableByteChannel delegate, Consumer<Integer> bytesWrittenConsumer) {
    this.delegate = Preconditions.checkNotNull(delegate);
    this.bytesWrittenConsumer = Preconditions.checkNotNull(bytesWrittenConsumer);
  }

  @Override
  public int write(ByteBuffer src) throws IOException {
    int bytesWritten = delegate.write(src);
    bytesWrittenConsumer.accept(bytesWritten);
    return bytesWritten;
  }

  @Override
  public boolean isOpen() {
    return delegate.isOpen();
  }

  @Override
  public void close() throws IOException {
    delegate.close();
  }
}
